I want to lock DFB-LD spectrum (LW = 5MHz) inside etalon transmission peak using feedback mechanism for laser linewidth reduction and stabilization.How can achieve that goal ? What are the options I have ?
Check out Sanford and Antill, "Laser frequency control using an optical resonator locked to an electronic oscillator," IEEE Journal of Quantum Electronics ( Volume: 33, Issue: 11, Nov 1997 ). A very elegant, doable and effective method for dramatically narrowing your DFB line width. Less dramatic and more self-referencing results can be found in "Wavelength stabilized, tunable optical transmitter with high SMSR," D A Ackerman - US Patent 6,064,681 which couples DFB lasers to low-Q FP, temperature insensitive etalons using electronic feedback and D. A. Ackerman et al., "Compact hybrid resonant optical reflector lasers with very narrow line widths," Appl. Phys. Lett. 58, 449 (1991) which achieves a 10kHz line and is in total quite a bit smaller than a dime. But really, check out the first reference.